Currently, broadcast and/or multicast service such as enhanced Multimedia Broadcast Multicast Service (eMBMS for short) is employed more and more widely in radio communication network. RP-090350 in LTE Release 9 requires that Multimedia Broadcast Multicast service Single Frequency Network (MBSFN for short) can provide good support for MBMS service. Each Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network (eNB) cell in the same MBSFN region uses the same time/frequency resource to send MBMS service, so as to make the service signal of each cell overlap with each other on the air, thereby providing UEs with the radio frequency (RF) combining gain and facilitating its reception and extraction of the MBMS service data.
Statistical Multiplexing (SM for short) can be carried out for different MBMS service with the same Quality of Service (QoS); these services can be transmitted in one MCH (multicast channel). Services that can be statistically multiplexed are defined as a “Service Bundle”. A single service, not statistically multiplexed, can be seen as a service bundle containing only one service. And one service bundle can be seen as one service during scheduling.
Currently, the multicast coordination entity (MCE) in the network determines a semi-static MCH Subframe Allocation Pattern (MSAP for short) for each service, according to the QoS of the service. The MSAP determines the maximum resource occupation of each service in each period. On the other hand, the MCE also determines the transmission priority and MCS for each service according to the QoS of the service. In the practical system, however, the number of the subframes practically occupied by the service might be smaller than the predefined number of subframes in the MSAP allocated by the MCE. Therefore, in order to better utilize the subframes not being practically occupied and improve resource utilization, the radio system can carry out dynamic MAC layer scheduling for the amount of resources, namely the number of subframes occupied by data transmission in each scheduling period, according to the real-time fluctuation of eMBMS service data; the granularity of scheduling takes one subframe as its unit. This real-time processing can be done via MAC dynamic scheduling in each scheduling period. For supporting statistical multiplexing and improving radio resource utilization, the services in statistical multiplexing are transmitted continuously. Padding is only added to the last subframe of each MCH in the scheduling period. The remaining subframes, those not being practically occupied by MBMS services transmissions and discovered after the scheduling, can be used for other services such as unicast.
FIG. 1 shows one example of MBMS dynamic scheduling based on MSAP. For example, where, #0, #4, #5 and #9 subframes of each frame need to be used for transmitting control information such as paging information and system information, the standard specifies that #0, #4, #5 and #9 subframes can not be defined as MBSFN transmission subframes. Thus, in this case, the system determines the MBSFN subframes as #1, #2 and #3 subframes in each frame. Meanwhile, the system determines that the previous 10 radio frames of each scheduling period can be used for carrying MBSFN subframes. This means that, the total number of subframes for MSAP during a scheduling period of 320 ms is 30. In this case, the subframe occupations for MSAP are the MBSFN subframes in consecutive several frames starting from the first frame.
There are 3 services S1, S2 and S3 participating the SM. These 3 services constitute a service bundle {S1, S2, S3}. The MCE calculates 8 subframes for this service bundle according to the QoS and service amount of the three services, and its occupations are the subframes #1, #2 and #3 in first and second radio frame, and subframes #1 and #2 in the third radio frame, as shown in FIG. 1. The MCE predefines this allocation result in MSAP and provides each eNB and UE with it. However, since the practical data rate of each service fluctuates, as shown in FIG. 1, practical transmission of data of the three services only occupies 6.5 subframes (wherein S1 shown in backslash block occupies 2.5 subframes; S2 shown in square block occupies 3 subframes; and S3 shown in slash block occupies 1 subframe). Therefore, after the eNB carries out dynamic scheduling for the three services, the subframe not being practically used, shown in the dash block, can be spared. The eNB can allocate this subframe for services such as unicast. Padding is only added to the last subframe of each MCH in the scheduling period, as shown in the pipe block in FIG. 1.
Because the MBMS dynamic scheduling takes a longer time as its period, the eMBMS scheduling is different from the unicast scheduling: the MBMS scheduling has a higher real-time requirement than the unicast scheduling. Thus, for physical multicast channel (PMCH), there is no dedicated control channel similar to the physical downlink control channel (PDCCH) for the physical downlink shared channel (PDSCH). Therefore, how to transmit to the UE the MBMS dynamic scheduling control information of each scheduling period, namely how to indicate to the UE the practical transmission of each service in each scheduling period, is a technical problem to be solved.